First things first.
Get a new mechanic - he knows fuck all.
Are your calipers 2 or 4wd calipers - if 2wd that will expalain the vague pedal feel and travel due to the fact they're rigid calipers and not floating like 4wd. This is because they dont need to be floating on a 2wd.
You can remove the ABS very simply if you have the correct brake line making tool and pipe - you dont even need to remove the ABS mechanism - but you will need to short the circuit or the light will come on and fail your MOT.
But back to the original question.
The ABS on your RST is unlikely to work anyway and to getting it to work is unlikely - look in a haynes manual to understand why.
So bin it.
The cons are that if you're a shit young driver you'll go straight up someones arse at the first sign of trouble - but then it prob didn't work in the first place anyways.
J